Electric devices not having a built-in power supply generally have at least one electrical connecting line (e.g., at least one cable). A cable may be connected via an electrical plug-in connection to a housing of an electric device or led through an opening of the housing into the interior of the housing to contact internal device components. In the latter case, the cable should be secured to the housing so that the electrical connection does not become destroyed by low tensile forces acting on the cable. The means and arrangements used for this purpose are generally referred to as strain relief devices. The phrase “electric device” (or “electrical device”) is to be understood to include outlets such as connection sockets and connectors such as plug-in connectors.
The functional principle of strain relief for a connecting line is generally based on fixing the connecting line in a clamping manner by joining together housing parts or by tightening a mechanical fastener (e.g., screw) connection to the housing.
In many cases, the housing of an electric device is made up of two joinable parts. After being joined together the joinable parts clamp the connection line between them at a location designated for this purpose. However, this type of strain relief does not function properly when the connection line to be fastened to the housing is a rigid cable having a relatively large cross section. In particular, when multiple cables are to be attached to the housing it is advantageous to provide fastening means particularly suited for this purpose.
DE 10 2010 007 093 A1 (corresponding to U.S. Publication No. 2012/0292098) describes an electric device having a cable feedthrough through a housing wall. A connection socket, in particular for a photovoltaic system, having two cable inlet ports is integrally formed on the housing. Relatively rigid, shielded, high-voltage cables are led into the interior of the housing respectively through the cable inlet ports. Each cable is fastened by crimping a sleeve on the outer sheathing of the cable. An annular surface on the sleeve is placed against the end face of the corresponding cable inlet port and is fastened by a union nut screwable onto the cable inlet port.
Establishing this type of cable fastening involves a relatively high level of assembly effort. This is due to the crimping operation initially carried out followed by the comparatively large time expenditure for subsequently establishing the screw connection. Therefore, such a design has limited suitability for electric devices manufactured in large amounts and to which multiple cables are to be fastened.